Organic EL display panels using organic EL elements are known as display panels which use current-driven light-emitting elements. Such organic EL display panels have gained much attention as candidates for next-generation flat panel displays (FPDs) because of such advantages as excellent viewing angle characteristics and low power consumption.
In an active-matrix organic EL display panel, pixels including organic EL elements are two-dimensionally arranged. A pixel circuit included in each of the pixels includes, for example, a thin-film transistor (TFT) provided at a crosspoint between a scanning line and a data line. The gate of a drive transistor is connected to the TFT, and by turning ON the TFT through a selected scanning line, a data signal is input from the data line to the drive transistor, and the organic EL element emits light.
In the above-described pixel configuration, miniaturization of circuit elements is advancing in response to increases in screen size and level of high-definition of display panels. As the miniaturization of circuit elements advances, circuit element inspecting techniques for ensuring the performance of the respective transistors and organic EL elements become increasingly important.
Patent Literature 1 discloses a method for inspecting a TFT substrate of a display device in a short time and with high precision. Specifically, an inspecting TFT, which has one of a source and a drain electrically connected to the drain of a drive TFT, and the other electrically connected to a signal line in an adjacent column, and a gate connected to the scanning line in the next row, inspects the output current of the drive TFT via the signal line in the adjacent column. Accordingly, since detection of the pixel current passed by the drive TFT and signal writing to the next row or the next column can be carried out in parallel, inspection time can be shortened.